The region is underlain by (?)Hadrynian to Paleozoic Snowshoe Group rocks. The Snowshoe Group is an assemblage of dominantly metasedimentary rocks within the Barkerville Terrane of south-central British Columbia. These metasedimentary rocks consist primarily of marble, quartzite and phyllite. In the Yanks Peak area these rocks comprise the Keithley and Harveys Ridge successions, but further to the east they remain undifferentiated. Metamorphism of the region varies from chlorite to sillimanite and higher grade. Gold-bearing quartz veins occur only in greenschist facies rocks.
A shaft is located just north of the road along Pearce Gulch Creek and the Bralco Cabin, 800 metres north of the Cariboo-Hudson mine (093A 071), about 23 kilometres southeast of Barkerville.
The Bralco quartz vein showings are scattered over a number of Crown grants which are underlain by rocks considered to belong to the Hardscrabble Mountain succession (Devono-Mississippian). Mineralization consists of galena, sphalerite, chalcopyrite and pyrite occurring in quartz veins which crosscut quartz sericite schist, phyllite and limestone. A 5.8-metre wide replacement zone in limestone is well mineralized with sphalerite and contains some pyrite and galena. Grades of two grab samples averaged 5.3 per cent lead, 15 per cent zinc and 30.9 grams per tonne silver (Assessment Report 6545).
North of the Bralco Cabin a shaft has been sunk on a sphalerite-bearing zone in a limestone unit. No literature is available on the old workings but Rio Tinto Canadian Exploration conducted an exploration program in the area between 1977 and 1979. The Bralco zinc showing was drilled in September and October of 1978. During 1972 and 1974, Coast Interior Ltd. conducted a base metal exploration program in the Roundtop area. Suncor Inc. has completed exploration programs in the area in 1981, 82 and 84. In 1988, Inter-Canadian Development Corp. conducted a VLF-EM survey and rock and soil sampling over a larger property that also covered the Bralco showing.